1. Field of the Invention
The present invention relates to a key switch device in which the vertical movement of a key top is guided by a pair of link members, and which performs a key clicking function when the key top is depressed, thereby achieving an excellent key operability; and a keyboard provided with the key switch device; and an electronic apparatus provided with the keyboard. Specifically, the present invention relates to a key switch device capable of performing a clear key clicking function by employing a specified relationship between link members and urging devices thereof, and thereby achieving an excellent key operability, without using a rubber spring which has been conventionally mounted in a key switch device of this type as a device for performing a key clicking function; a keyboard; and an electronic apparatus.
2. Description of the Related Art
In recent years, as a reduction in size and thickness of notebook-size personal computers and various kinds of mobile computer devices has been promoted, the size and thickness of a key switch device in a keyboard associated with these devices have been also remarkably reduced. In this situation, in order to provide key switch devices having reduced size and thickness, there have been proposed various key switch devices in which the vertical (upward and downward) movement of the key top is guided by a pair of link members.
Among the key switch devices such as described above, there is a key switch device having the following structure. A first and second engagement portions are provided on the underside of the key top, and a holder member is provided below the key top. The key top is formed with a third engagement portion which corresponds to the first engagement portion, and a fourth engagement portion which corresponds to the second engagement portion. An upper end portion of one of the link members is rotatably engaged in the first engagement member, while the lower end portion thereof if slidably engaged in the third engagement portion. On the other hand, an upper end portion of the other link member is rotatably engaged in the second engagement portion, while the lower end portion thereof is slidably engaged in the fourth engagement portion.
There has been also known another key switch device having the following structure. A key top and a holder member are constituted to have the same structure as those of the key switch device described above. Two link members are in a crosslink structure in which they are pivotally supported so as to be rotatable with respect to each other. In addition, an upper end portion of one of the link members is rotatably engaged in the first engagement portion of the key top, while a lower end portion thereof is slidably engaged in the fourth engagement portion of the holder. On the other hand, an upper end portion of the other link member is slidably engaged in the second engagement portion, while a lower end portion thereof is rotatably engaged in the third engagement portion.
In both types of the key switch devices described above, the vertical movement of the key top is guided by a link structure of the two link members. In this manner, neither a key stem nor its guide structure is required, thereby attaining a reduction in size and thickness of the key switch devices. In addition, the key top can be vertically moved with its horizontal condition is maintained regardless the depression condition or situation of the key top.
In the key switch devices described above, a sufficient response from the key when the key top is depressed to the deepest position contributes to an increased key operability. In an attempt to achieve such a response from the key, the key switch devices are provided with a mechanism for performing a key clicking function.
In the key switch devices described above, a key clicking function is generally performed by use of a so-called rubber spring. The rubber spring is mounted below the key top or each of the link members. When the key top is depressed, the rubber spring is compressed by the underside of the key top or the link members. Based on the compression characteristic of the rubber spring obtained when the rubber spring is compressed, the key clicking function is effected.
However, when a rubber spring is used as a mechanism for performing the key clicking function as is the case of the key switch devices described above, the key clicking function is determined by the shape, thickness, and size of the rubber spring itself, and the shapes and sizes of the key top and each link member constituting the key switching mechanism. In the current state of the art, in order to perform a desired key clicking function to be given to a key switch device, trials for the rubber spring and the key switching mechanism are conducted in several times, and test and fault is repeated to determine the final rubber spring and the key switching mechanism. This method has a problem that it requires much cost and takes much too long time to obtain a key switch device having a desired key clicking function.
The present invention has been made in view of the above circumstances and has an object to overcome the above problems and to provide a key switch device capable of simulating the characteristic of the key clicking function by designing link members and urging devices thereof to have a specified relationship therebetween, without using a rubber spring which has been conventionally mounted in a key switch device of general type as a device for performing a key clicking function, thereby realizing a key switch device having an excellent key operability with a desired key clicking function in a short period at low cost by suppressing the number of trials for the key switching mechanism to the minimum; a keyboard provided with the key switch device; and an electronic apparatus provided with the keyboard.
Additional objects and advantages of the invention will be set forth in part in the description which follows and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.
To achieve the purpose of the invention, there is provided a key switch device including: a key top provided at its underside with a first engagement portion and a second engagement portion; a third engagement portion corresponding to the first engagement portion, and a fourth engagement portion corresponding to the second engagement portion, both of which are arranged below the key top; a first link member provided with an upper end portion which is rotatably engaged in the first engagement portion and a lower end portion which is slidably engaged in the third engagement portion; a second link member provided with an upper end portion which is rotatably engaged in the second engagement portion and a lower end portion which is slidably engaged in the fourth engagement portion; an urging member for urging the first link member and the second link member in a direction to allow them to come close to each other; and a switching member for conducting a switching operation in association with vertical movement of the key top, the key switch device being designed to be symmetric with respect to a perpendicular line passing through a midpoint between the first engagement portion and the second engagement portion, wherein the upper end portion of the first link member is allowed to rotate about a predetermined rotation point in the first engagement portion, and the lower end portion of the first link member is allowed to slide outwardly from a predetermined slide starting point in the third engagement portion, an urging force of the urging member is exerted on the first link member at a predetermined acting point in the first link member, a depressing load applied to the key top when the key top is depressed is defined by a function expressed by: distance between the rotation point and the slide starting point; a distance between the rotation point and the acting point; an angle between a line segment extending from the rotation point to the slide starting point, and the direction along which the lower end portion of the first link member in the third engagement portion is allowed to slide; and various characteristic values of the urging member; and a curve of the depressing load defined by the function takes a shape of an upward projecting curve having a maximum point, and a key clicking function is performed based on a difference in loads between the maximum point and a point from which the depressing load starts to increase after the switching operation is conducted by the switching member.
According to another aspect of the present invention, there is provided a keyboard provided with at least one of the key switch device recited above.
According to another aspect of the present invention, there is provided an electronic apparatus including: a keyboard for inputting various data such as characters, symbols, and others, the keyboard being provided with a key switch device including: a key top provided at its underside with a first engagement portion and a second engagement portion; a third engagement portion corresponding to the first engagement portion, and a fourth engagement portion corresponding to the second engagement portion, both of which are arranged below the key top; a first link member provided with an upper end portion which is rotatably engaged in the first engagement portion and a lower end portion which is slidably engaged in the third engagement portion; a second link member provided with an upper end portion which is rotatably engaged in the second engagement portion and a lower end portion which is slidably engaged in the fourth engagement portion; an urging member for urging the first link member and the second link member in a direction to allow them to come close to each other; and a switching member for conducting a switching operation in association with vertical movement of the key top, the key switch device being designed to be symmetric with respect to a perpendicular line passing through a midpoint between the first engagement portion and the second engagement portion, wherein the upper end portion of the first link member is allowed to rotate about a predetermined rotation point in the first engagement portion, and the lower end portion of the first link member is allowed to slide outwardly from a predetermined slide starting point in the third engagement portion, an urging force of the urging member is exerted on the first link member at a predetermined acting point in the first link member, a depressing load applied to the key top when the key top is depressed is defined by a function expressed by: a distance between the rotation point and the slide starting point; a distance between the rotation point and the acting point; an angle between a line segment extending from the rotation point to the slide starting point, and the direction along which the lower end portion of the first link member in the third engagement portion is allowed to slide; and various characteristic values of the urging member; and a curve of the depressing load defined by the function takes a shape of an upward projecting curve having a maximum point, and a key clicking function is performed based on a difference in loads between the maximum point and a point from which the depressing load starts to increase after the switching operation is conducted by the switching member; display means for displaying the characters, symbols, and others; and control means for controlling the display means to display the characters, symbols, and others based on input data from the keyboard.
According to another aspect of the present invention, there is provided a key switch device including: a key top provided at its underside with a first engagement portion and a second engagement portion; a third engagement portion corresponding to the first engagement portion, and a fourth engagement portion corresponding to the second engagement portion, both of which are arranged below the key top; a first link member provided with an upper end portion which is rotatably engaged in the first engagement portion and a lower end portion which is slidably engaged in the third engagement portion; a second link member provided with an upper end portion which is rotatably engaged in the second engagement portion and a lower end portion which is slidably engaged in the fourth engagement portion; an urging member for urging the first link member and the second link member in a direction away from each other; and a switching member for conducting a switching operation in association with vertical movement of the key top, the key switch device being designed to be symmetric with respect to a perpendicular line passing through a midpoint between the first engagement portion and the second engagement portion, wherein the upper end portion of the first link member is allowed to rotate about a predetermined rotation point in the first engagement portion, and the lower end portion of the first link member is allowed to slide outwardly from a predetermined slide starting point in the third engagement portion, an urging force of the urging member is exerted on the first link member at a predetermined acting point in the first link member, a depressing load applied to the key top when the key top is depressed is defined by a function expressed by: a distance between the rotation point and the slide starting point; a distance between the rotation point and the acting point; an angle between a line segment extending from the rotation point to the slide starting point, and the direction along which the lower end portion of the first link member in the third engagement portion is allowed to slide; and various characteristic values of the urging member; and a curve of the depressing load defined by the function takes a shape of an upward projecting curve having a maximum point, and a key clicking function is performed based on a difference in loads between the maximum point and a point from which the depressing load starts to increase after the switching operation is conducted by the switching member.
According to another aspect of the present invention, there is provided a keyboard provided with at least one of the above key switch device.
According to another aspect of the present invention, there is provided an electronic apparatus including: a keyboard for inputting various data such as characters, symbols, and others, the keyboard being provided with a key switch device including: a key top provided at its underside with a first engagement portion and a second engagement portion; a third engagement portion corresponding to the first engagement portion, and a fourth engagement portion corresponding to the second engagement portion, both of which are arranged below the key top; a first link member provided with an upper end portion which is rotatably engaged in the first engagement portion and a lower end portion which is slidably engaged in the third engagement portion; a second link member provided with an upper end portion which is rotatably engaged in the second engagement portion and a lower end portion which is slidably engaged in the fourth engagement portion; an urging member for urging the first link member and the second link member in a direction away from each other; and a switching member for conducting a switching operation in association with vertical movement of the key top, the key switch device being designed to be symmetric with respect to a perpendicular line passing through a midpoint between the first engagement portion and the second engagement portion, wherein the upper end portion of the first link member is allowed to rotate about a predetermined rotation point in the first engagement portion, and the lower end portion of the first link member is allowed to slide outwardly from a predetermined slide starting point in the third engagement portion, an urging force of the urging member is exerted on the first link member at a predetermined acting point in the first link member, a depressing load applied to the key top when the key top is depressed is defined by a function expressed by: a distance between the rotation point and the slide starting point; a distance between the rotation point and the acting point; an angle between a line segment extending from the rotation point to the slide starting point, and the direction along which the lower end portion of the first link member in the third engagement portion is allowed to slide; and various characteristic values of the urging member; and a curve of the depressing load defined by the function takes a shape of an upward projecting curve having a maximum point, and a key clicking function is performed based on a difference in loads between the maximum point and a point from which the depressing load starts to increase after the switching operation is conducted by the switching member; display means for displaying the characters, symbols, and others; and control means for controlling the display means to display the characters, symbols, and others based on input data from the keyboard.
According to another aspect of the present invention, there is provided a key switch device including: a key top provided at its underside with a first engagement portion and a second engagement portion; a third engagement portion corresponding to the first engagement portion, and a fourth engagement portion corresponding to the second engagement portion, both of which are arranged below the key top; a guide member including: a first link member provided with an upper end portion which is rotatably engaged in the second engagement portion and a lower end portion which is slidably engaged in the third engagement portion, and a second link member provided with an upper end portion which is rotatably engaged in the first engagement portion and a lower end portion which is slidably engaged in the fourth engagement portion, the first and second link members being pivotally supported to be rotatable with respect to each other; an urging member for urging the first link member and the second link member in a direction to allow them to pivotally rotate about a shaft supporting point; and a switching member for conducting a switching operation in association with vertical movement of the key top, the key switch device being designed to be symmetric with respect to a perpendicular line passing through a midpoint between the first engagement portion and the second engagement portion, wherein the upper end portion of the first link member is allowed to rotate about a predetermined rotation point in the second engagement portion, and the lower end portion of the first link member is allowed to slide outwardly from a predetermined slide starting point in the third engagement portion, an urging force of the urging member is exerted on the first link member at a predetermined acting point in the first link member, a depressing load applied to the key top when the key top is depressed is defined by a function expressed by: a distance between the rotation point and the slide starting point; a distance between the rotation point and the acting point; a distance between the rotation point and the shaft supporting point; an angle between a line segment extending from the rotation point to the slide starting point, and the direction along which the lower end portion of the first link member in the third engagement portion is allowed to slide; and various characteristic values of the urging member; and a curve of the depressing load defined by the function takes a shape of an upward projecting curve having a maximum point, and a key clicking function is performed based on a difference in loads between the maximum point and a point from which the depressing load starts to increase after the switching operation is conducted by the switching member.
According to another aspect of the present invention, there is provided a keyboard provided with at least one of the above key switch device.
According to another aspect of the present invention, there is provided an electronic apparatus including: a keyboard for inputting various data such as characters, symbols, and others, the keyboard being provided with a key switch device including: a key top provided at its underside with a first engagement portion and a second engagement portion; a third engagement portion corresponding to the first engagement portion, and a fourth engagement portion corresponding to the second engagement portion, both of which are arranged below the key top; a guide member including: a first link member provided with an upper end portion which is rotatably engaged in the second engagement portion and a lower end portion which is slidably engaged in the third engagement portion, and a second link member provided with an upper end portion which is rotatably engaged in the first engagement portion and a lower end portion which is slidably engaged in the fourth engagement portion, the first and second link members being pivotally supported to be rotatable with respect to each other; an urging member for urging the first link member and the second link member in a direction to allow them to pivotally rotate about a shaft supporting point; and a switching member for conducting a switching operation in association with vertical movement of the key top, the key switch device being designed to be symmetric with respect to a perpendicular line passing through a midpoint between the first engagement portion and the second engagement portion, wherein the upper end portion of the first link member is allowed to rotate about a predetermined rotation point in the second engagement portion, and the lower end portion of the first link member is allowed to slide outwardly from a predetermined slide starting point in the third engagement portion, an urging force of the urging member is exerted on the first link member at a predetermined acting point in the first link member, a depressing load applied to the key top when the key top is depressed is defined by a function expressed by: a distance between the rotation point and the slide starting point; a distance between the rotation point and the acting point; a distance between the rotation point and the shaft supporting point; an angle between a line segment extending from the rotation point to the slide starting point, and the direction along which the lower end portion of the first link member in the third engagement portion is allowed to slide; and various characteristic values of the urging member; and a curve of the depressing load defined by the function takes a shape of an upward projecting curve having a maximum point, and a key clicking function is performed based on a difference in loads between the maximum point and a point from which the depressing load starts to increase after the switching operation is conducted by the switching member; display means for displaying the characters, symbols, and others; and control means for controlling the display means to display the characters, symbols, and others based on input data from the keyboard.